Bridging DMB structure for wire bonding in a power semiconductor module

ABSTRACT

A power module includes a substrate DMB (Direct Metal Bonded). A novel bridging DMB is surface mounted to the substrate DMB along with power semiconductor device dice. The top metal layer of the bridging DMB has one or more islands to which bonding wires can connect. In one example, an electrical path extends from a module terminal, through a first bonding wire and to a first location on a strip-shaped island, through the island to a second location, and from the second location and through a second bonding wire. The strip-shaped island of the bridging DMB serves as a section of the overall electrical path. Another bonding wire of a separate electrical path passes transversely over the strip-shaped island without any wire crossing any other wire. Use of the bridging DMB promotes bonding wire mechanical strength as well as heat sinking from bonding wires down to the substrate DMB.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority under 35U.S.C. §120 from, nonprovisional U.S. patent application Ser. No.14/929,308 entitled “Bridging DMB Structure for Wire Bonding in a PowerSemiconductor Device Module,” filed on Oct. 31, 2015, now U.S. Pat. No.9,443,792, the subject matter of which is incorporated herein byreference.

TECHNICAL FIELD

The described embodiments relate to power semiconductor device modules.

BACKGROUND INFORMATION

A type of power semiconductor device module includes an injection moldedplastic housing. The injection molded housing has a frame-shape thatextends around a metal baseplate so that the housing and the metalbaseplate together form a tray-shaped recess. The metal baseplate formsthe bottom of the tray. Disposed on the top of the metal baseplate inthe bottom of the tray is a DMB (Direct Metal Bonded) and semiconductordevice assembly. The DMB and semiconductor device assembly includes aDMB structure. The DMB structure is a multi-layer structure thatincludes an insulative but heat-conductive center ceramic substratelayer. A planar bottom direct metal bonded metal layer is bonded to thebottom surface of the ceramic layer, and a planar top direct metalbonded metal layer is bonded to the top surface of the ceramic layer.The top direct metal bonded metal layer is patterned into a plurality ofislands of metal. Discrete semiconductor device dice are surface mountedto the various islands on the top the DMB structure in a way consistentwith an overall power device circuit to be realized by the module. Thevarious discrete semiconductor device dice and various portions of theDMB structure are interconnected by bonding wires, both to each other,as well as to external connection terminals of the module, such that theoverall wire bonded assembly is a desired power device circuit. Theassembly within the tray is then covered over with a layer of softsilicone gel or other soft encapsulant. A plastic cap is then fixed overthe top of the tray. Such power semiconductor device modules seewidespread use in the power semiconductor device industry. Ways ofimproving such power semiconductor device modules are sought.

SUMMARY

A power semiconductor device module includes a housing that forms atray. For example, an injection molded housing along with a metalbaseplate can form a central shallow tray structure. The top surface ofthe metal baseplate is the bottom of the tray. Disposed on the topsurface of the metal baseplate in the bottom of the tray is a DMB(Direct Metal Bonded) and semiconductor device assembly. Covering thisassembly on the bottom of the tray is a layer of an encapsulant, such asa layer of soft silicone gel material. An injection molded plastic capis fitted over the top of the tray to cover the encapsulant and the DMBand semiconductor device assembly within the module. A ring ofupward-extending metal external connection terminals extends around theperipheral edge of the plastic housing.

The DMB and semiconductor device assembly includes a substrate DMBstructure. A top metal layer of the substrate DMB structure is patternedinto a plurality of islands. Power semiconductor device dice are surfacemounted to some of these islands. A novel bridging DMB structure is alsosurface mounted to the top of the substrate DMB structure. There is nosemiconductor device die mounted to this bridging DMB structure, butrather the bridging DMB structure serves as a bridge for wire or ribbonbonding. In one example, a first electrical path extends from anexternal connection terminal of the module, through a first bondingwire, to a first connection location on a strip-shaped island of thebridging DMB structure, through the strip-shaped island to a secondconnection location on the bridging DMB structure, and from the secondconnection location on the bridging DMB structure and through a secondbonding wire to a bonding pad on the top of one of the semiconductordevice dice. The strip-shaped island serves as a section of the overallfirst electrical path. A third bonding wire of a second electrical pathpasses transversely over the strip-shaped island without any of thebonding wires crossing any other bonding wire.

In some examples, a bond wire extends from a first location on abridging DMB structure to another location on the bridging DMBstructure. Such a bridging bonding wire can pass over another island onthe top of the bridging DMB structure, or may not pass over any suchother island. The bottom layer of metal of a substrate DMB structure canbe patterned into multiple islands, such that the bottom metal layer ofthe bridging DMB structure can be physically bonded to multipleunderlying traces of the substrate DMB structure, without the bottommetal of the bridging DMB structure shorting those traces (islands ofthe substrate DMB structure) together. In one advantageous embodiment,electrical paths passing through and/over the top metal of the bridgingDMB structure are relatively low current paths such as gate currentpaths and auxiliary emitter current paths, whereas other electricalpaths passing underneath the bridging DMB structure are relatively highcurrent paths such as emitter current connections and collector currentconnections. Use of the bridging DMB in power semiconductor devicemodules allows more current carrying metal to be provided in thesubstrate DMB structure for the relatively high current paths, increasesmechanical strength of bonding wires, helps prevent shorting betweenbonding wires, and promotes heat sinking from bonding wires down to thesubstrate DMB structure.

Further details and embodiments and techniques are described in thedetailed description below. This summary does not purport to define theinvention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, where like numerals indicate like components,illustrate embodiments of the invention.

FIG. 1 is a top-down perspective diagram of a power semiconductor devicemodule in accordance with one novel aspect.

FIG. 2 is a circuit diagram of the circuitry within the powersemiconductor device module of FIG. 1.

FIG. 3 is a side view diagram of the power semiconductor device moduleof FIG. 1.

FIG. 4 is a top-down diagram of the power semiconductor device module ofFIG. 1.

FIG. 5 is a top-down diagram of one of the IGBT dice within the powersemiconductor device module of FIG. 1.

FIG. 6 is a top-down diagram of one of the diode dice within the powersemiconductor device module of FIG. 1.

FIG. 7 (Prior Art) is top-down diagram of a prior art powersemiconductor device module that has crossing bonding wires.

FIG. 8 is a top-down diagram of the novel power semiconductor devicemodule of FIG. 1 that has two novel bridging DMB structures andassociated bonding wires.

FIG. 9 is a diagram that shows the lower left portion of FIG. 8 inexpanded fashion.

FIG. 10 is a cross-sectional diagram taken along sectional line A-A′ ofFIG. 9.

FIG. 11 is a perspective diagram of the top of a novel bridging DMBstructure.

FIG. 12 is a perspective diagram of the bottom of the novel bridging DMBstructure of FIG. 11.

FIG. 13 is an expanded cross-sectional diagram that shows how two novelbridging DMB structures are bonded to the substrate DMB structure withinthe semiconductor device module of FIG. 1.

FIG. 14 is a diagram of another bridging DMB structure.

FIG. 15 is a diagram of the bottom of the bridging DMB structure of FIG.14.

FIG. 16 is a diagram of another bridging DMB structure.

DETAILED DESCRIPTION

Reference will now be made in detail to background examples and someembodiments of the invention, examples of which are illustrated in theaccompanying drawings. In the description and claims below, when a firstobject is referred to as being disposed “over” or “on” a second object,it is to be understood that the first object can be directly on thesecond object, or an intervening object may be present between the firstand second objects. Similarly, terms such as “upper”, “top”, “up”,“down”, “vertically”, “horizontally”, “laterally”, “lower”, “under”,“below”, “beneath” and “bottom” are used herein to describe relativeorientations between different parts of the structure being described,and it is to be understood that the overall structure being describedcan actually be oriented in any way in three-dimensional space.

FIG. 1 is a top-down perspective diagram of a power semiconductor devicemodule 36 in accordance with one novel aspect. The power semiconductordevice module 36 includes an injection molded plastic housing 37 thatalong with a metal baseplate 38 forms a central shallow tray-shapedrecess or depression. The plastic housing 37 extends around and framesthe metal baseplate. The metal baseplate 38 forms the bottom of thetray. Solder joined to the top surface of the metal baseplate 38 in thebottom of the tray is a DMB (Direct Metal Bonded) and semiconductordevice assembly. Covering this assembly on the bottom of the tray is alayer of an encapsulant, such as a layer of soft silicone gel material39. A plastic cap 86 is then fitted over the top of the tray to coverthe encapsulant and the open face of the tray. A ring ofupward-extending metal external connection terminals 1-35 extends aroundthe peripheral edge of the plastic housing 36 as shown in FIG. 1. As isdescribed in further detail below, these metal external connectionterminals are electrically coupled to various points of the electricalcircuit of the DMB and semiconductor device assembly within the module.The module can be attached to a heatsink via screws (not shown) so thatthe metal baseplate of the module is pressed against the heatsink to bein good thermal contact with the heatsink. The screws are made to extendthrough mounting holes 40-43 in the housing 37 so that heads of thescrews hold the module against the heatsink. In the particularembodiment illustrated, there are four mounting holes 40-43 foraccommodating four such mounting screws. One mounting hole is located ateach corner of the housing.

FIG. 2 is a circuit diagram of the DMB and semiconductor device assemblyof the module 36. The reference numerals 1-35 on the diagram of FIG. 2correspond to the reference numerals 1-35 on FIG. 1. The assemblyincludes numerous discrete power semiconductor device dice. There aresix discrete IGBT (Insulated Gate Bipolar Transistors) dice denotedIGBT#1 through IGBT#6 and there are six discrete diode dice denoted D#1through D#6. Each discrete IGBT die has a collector terminal and contact(denoted “C”), an emitter terminal and contact (denoted “E”), a gateterminal and contact (denoted “G”), and an auxiliary emitter terminaland contact (denoted “AUXE”). Each discrete diode die has an anodeterminal (denoted “A”) and a cathode terminal (denoted “C”). The IGBTand diode dice are surface mounted directly to a substrate DMB structure53 of the assembly.

FIG. 3 is a side view diagram of the power semiconductor device module36 of FIG. 1.

FIG. 4 is a top-down diagram of the power semiconductor device module 36of FIG. 1.

FIG. 5 is a top-down diagram of one of the IGBT dice, IGBT#1. All of thesix IGBT dice of the DMB and semiconductor device assembly areidentical. The IGBT die 49 includes a gate contact 44 and four emittercontracts 45-48 disposed on the top surface of the die 49. The bottomsurface of the die (not shown) is a collector contact of the die.

FIG. 6 is a top-down diagram of one of the diode dice, D#1. All of thesix diode dice of the DMB and semiconductor device assembly areidentical. Die 51 includes an anode contact 50 disposed on the topsurface of the die 51, and a cathode contact (now shown) on the bottomof the die. In each pair IGBT/diode pair, the anode of the diode iscoupled to the emitter of the IGBT, and the cathode of the diode iscoupled to the collector of the IGBT.

FIG. 7 is top-down diagram of a prior art semiconductor device module200 (Prior Art). The cap 86 and the soft silicone gel encapsulant 39 arenot shown in the diagram of FIG. 7 so that the top of DMB andsemiconductor device assembly can be seen. The module of FIG. 7 has thecircuit diagram of FIG. 2 and has the same pinout as illustrated in FIG.1, FIG. 3 and FIG. 4. The IGBT dice, from top to bottom, in the verticalcolumn orientation shown in FIG. 7, are denoted IGBT#6, IGBT#5, IGBT#4,IGNT#3, IGBT#1 and IGBT#2. The diode dice, from top to bottom, in thevertical column orientation shown in FIG. 7, are denoted D#6, D#5, D#4,D#3, D#1 and D#2. The pinout of the module 200 is determined by externalcircuitry and/or by customer requirements, yet within the module theIGBT dice are oriented as shown. Consequently, bonding wires from thegate terminal 201 and from the auxiliary emitter terminal 202 to thegate contact 213 and to the emitter contact 214 of IGBT#2 cross withrespect to the bonding wires from the gate terminal 203 and from theauxiliary emitter terminal 204 to the gate contact 205 and to theemitter contact 206 of IGBT#1. Advantageously, the length of bondingwires extending between bonding locations is adequately small, andthermal transfer from the bonding wires down to the substrate DMB anddown to the metal baseplate beneath it is enhanced, due to the bondingwires being bonded to islands 207-210 of conductive metal of the upperlayer of metal of the substrate DMB 211. The islands 207-210advantageously provide mechanical stability to the bonding wires, andalso serve to remove heat from the bonding wires. The IGBT module 200 ofFIG. 7 works well in its intended environment. Heat from the bondingwires is successfully conducted from the bonding wires, down through theislands 207-210, to the substrate DMB 211 below, and to the metalbaseplate 212 below that. The bonding wires that cross aresatisfactorily short as compared to the other bonding wires of themodule.

FIG. 8 is a top-down diagram of the power semiconductor device module 36of FIG. 1. The cap 86 and the soft silicone gel encapsulant 39 are notshown in the diagram of FIG. 8 so that the top of the DMB andsemiconductor device assembly can be seen. The module 36 actuallyincludes two major substrate DMB structures 52 and 53. The upper directbonded metal layer 60 of substrate DMB structure 53 is patterned intomultiple metal islands 54-59. Reference numeral 61 identifies the centerceramic layer of substrate DMB structure 53. The bottom direct bondedmetal layer 62 of substrate DMB structure 53 is not shown because it ison the bottom of the DMB in contact with the upper surface of theunderlying metal 38. Likewise, the upper direct bonded metal layer ofsubstrate DMB structure 52 is patterned into multiple metal islands. Thebottom direct bonded metal layer of substrate DMB structure 52 is notshown because it is on the bottom of the DMB in contact with the uppersurface of the underlying metal 38.

The central insulative but thermally conductive ceramic layer of a DMBstructure can, for example, be alumina (Al₂O₃) or aluminum nitride(AlN). The metal layers of a DMB structure can, for example, be copperor aluminum. In the case of copper metal layers, the DMB structure maybe called a DBC (“Direct-Bonded Copper”) substrate or a DCB (“DirectCopper Bonded”) substrate. In the case of aluminum metal layers, the DMBstructure may be called a DBA (“Direct-Bonded Aluminum”) substrate or aDAB (“Direct Aluminum Bonded”) substrate. For additional details on DMBsubstrates, see: U.S. Pat. No. 6,404,065, U.S. Pat. No. 6,798,060, andU.S. Pat. No. 7,005,734 (the entire subject matter of each of thesethree patent documents is incorporated herein by reference).

The DMB and semiconductor device assembly, in addition to the substrateDMB structures 52 and 53, and the IGBT dice, and the diode dice, andheavy aluminum bonding wires, includes two novel bridging DMB structures63 and 64.

FIG. 9 is a diagram that shows the lower left portion of FIG. 8 inexpanded fashion. As compared to the module structure of FIG. 7 wherethere are crossing bonding wires, there are no crossing bonding wires inthe novel module structure of FIG. 9. In the example of FIG. 9, eachexternal connection terminal has a vertically extending pin portion anda laterally extending wiring pad portion. The wiring pad portion issometimes called a “foot”. Each external connection terminal is astamped, formed and bent piece of metal that is press fit down into anaccommodating insertion channel in the plastic of the housing so thatthe terminal is held in place with respect to the housing. (In otherexamples, the external connection terminals are not inserted (pressfit), but rather are transfer molded into the plastic housing.) A firstbonding wire 65 extends from the wiring pad 66 of the externalconnection terminal 10 to a first bonding location 67 on DMB wirebonding bridge structure 63. A first direct bonded metal layer 68 ofbridging DMB structure 63 is disposed on the bottom of a ceramic layer69 of the bridging DMB structure 63. This first direct bonded metallayer 68 is not seen in FIG. 9 because it is disposed underneath ceramiclayer 69, and is disposed on and attached to metal island 54 of DMBstructure 53. Island 54, which is an elongated conductive strip-shapedstructure, is a metal trace and serves to conduct large currents fromthe emitters of IGBT#5, IGBT#3 and IGBT#1 to the external connectionterminals 13, 14 and 15. This current flows through the elongated traceof metal under the bridging DMB structure 63. A second direct bondedmetal layer 70 of the bridging DMB structure 63 is disposed on the topof the ceramic layer 69 of the bridging DMB structure 63. This seconddirect bonded metal layer is patterned into two elongatedparallel-extending strip-shaped islands 71 and 72. The bonding location67 is toward the upper end of island 71. A second bonding location 73 istoward the bottom end of the island 71. A second bonding wire 74 extendsfrom the second bonding location 73 to the emitter contact 75 of IGBT#2.Reference numerals 75-78 identify emitter contacts on the upper surfaceof IGBT#2. A third bonding wire 79 extends from the wiring pad 80 ofexternal connection terminal 12, up and over and across the bridging DMBstructure 63, and to an strip-shaped island 81 of the upper directbonded metal layer 83 of bridging DMB structure 64. The first and secondbridging DMB structures 63 and 64 are of identical construction in thisembodiment. Reference numerals 81 and 82 identify elongated strip-shapedislands of the upper direct bonded metal layer 83 of the bridging DMBstructure 64. A bottom direct bonded metal layer 84 of the bridging DMBstructure 64 is not shown in the diagram because it is disposedunderneath the ceramic layer 85 of the bridging DMB structure 64. Thethird bonding wire 79 does not contact any part of bridging DMBstructure 63. The third bonding wire 79 passes over bridging DMBstructure 63 at a crossing location between the first bonding location67 and the second bonding location 73. In FIG. 9, reference numerals86-91 identify some of the other bonding wires of the assembly. In theillustration, a dot at a point on a bonding wire represents a bondinglocation. Reference numeral 92 represents a gate contact. Of importance,the width of island trace 54, where the island trace passes under thebridging DMB structure 63, is not narrowed due to having to providebonding islands 207-210 as in the case of FIG. 7. The cross-section ofmetal of the island trace 54 of FIG. 9 is larger as compared thecross-section of metal in the island trace 215 of FIG. 7. Moreover,there is also conductive metal provided in the first (bottom) directbonded metal layer 68 of bridging DMB structure 63. There is also anamount of conductive solder 93 used to join the bottom of DMB 63 to thetop of island trace 54. As compared to a simple point-bonding contactlocated approximately midway along the length of a bonding wire as inthe case of FIG. 7, there is better thermal transfer between the bondingwire connections of FIG. 9 and the underlying metal 38 due to the largecontact metal contact area on the bottom of the bridging DMB structure63. This large metal contact area forms a superior thermal contact tothe underlying heat sinking structures.

In addition to the advantage of allowing the current carryingcross-sectional area of metal traces passing underneath the bridging DMBstructures to be maximized, use of the bridging DMB structures alsoallows the maximum length of the bonding wires to be shortened ascompared to the prior art structure of FIG. 7. In the case of using thenovel bridging DMB structures, some of the distance of a connection (forexample, the connection between terminal 10 and emitter contact 75) maybe provided by a part of a strip-shaped island on the top of a DMBstructure. As a result, the longest section of bonding wire of theoverall connection can be made shorter than in the prior art structureof FIG. 7. Shortening bonding wires serves to increase the mechanicalstrength of the bonding wires and to reduce their susceptibility tobreakage, especially at their bonding locations. Providing a section ofthe overall connection in the form of an island on the top of a bridgingDMB structure also allows there to be more cross-sectional area ofcurrent carrying metal in the DMB section of the overall connection ascompared to a prior art situation where all current was conductedthrough bonding wires. If even more current carrying metal is desired,then a bonding wire can be made to extend in parallel across the top ofa strip-shaped island, with the parallel-extending bond wire beingconnected down to the strip-shaped island at various points along itslength, thereby effectively increasing the amount of current carryingmetal even more.

The bridging DMB structures in this embodiment are small structures usedfor bridge wiring, and particularly for bridge wiring in the narrowspace between the vertical column of IGBT device of FIG. 8 and the leftedges of the module of FIG. 8. There is no semiconductor device mountedto the top of either of the two bridging DMB structures. Each of thediscrete semiconductor IGBT and diode devices of FIG. 8 has a major topsurface area. The bridging DMB structures of FIG. 8 also have a majortop surface area. The major top surface area of each of the discretesemiconductor devices is larger than the major top surface area of eachof the bridging DMB structures. This small size of the bridging DMBstructures facilitates use of the same bridging DMB structure at variouslocations around the discrete semiconductor device, without introducinga need either to change the patterning of a substrate DMB structure orto change the mounting locations of the various semiconductor deviceswithin the module.

FIG. 10 is a simplified cross-sectional diagram taken along sectionalline A-A′ of FIG. 9. The bridging DMB structure 63 includes the bottomdirect bonded metal layer 68, the central ceramic layer 69, and theparallel-extending strip-shaped islands 71 and 72 of the upper directbonded metal layer 70. The bridging DMB structure 64 includes the bottomdirect bonded metal layer 84, the central ceramic layer 85, and theparallel-extending strip-shaped islands 82 and 81 of the upper directbonded metal layer. The bridging DMB structure 63 is joined to DMBstructure 53 by solder 93. The bridging DMB structure 64 is joined toDMB structure 53 by solder 94.

FIG. 11 is a perspective diagram of the top of the bridging DMBstructure 63.

FIG. 12 is a perspective diagram of the bottom of the bridging DMBstructure 63.

FIG. 13 is an expanded cross-sectional diagram that shows how the twobridging DMB structures 63 and 64 are bonded to the substrate DMBstructure 53.

FIG. 14 is a top-down diagram of another embodiment of a bridging DMBstructure 300. Reference numeral 301 identifies the square-shaped centerceramic layer. The upper direct bonded metal layer of the DMB structure300 is patterned into six islands 302-307 having shapes as illustratedin FIG. 14. The bridging DMB structure 300 is shown mounted over and onthe two parallel-extending strip-shaped islands 54 and 55 of theunderlying substrate DMB structure 53. These strip-shaped islands 54 and55 are the islands illustrated in FIG. 9. Bonding wires 308 and 309couple external connection gate terminal 9 to the gate contact 92 ofIGBT#2. Bonding wires 310 and 311 couple external connection auxiliaryemitter terminal 10 to emitter contact 76 of IGBT#2. Bonding wire 312couples external connection gate terminal 11 to the gate contact 44 ofIGBT#1. Bonding wire 312 makes connection to the DMB structure 300 attwo different locations, and bridges up and over islands 305 and 304without making electrical contact to islands 305 and 304. Bonding wire314 couples external connection auxiliary emitter terminal 12 to emittercontact 48 of IGBT#1. Like bonding wire 312, bonding wire 314 makesconnection to the DMB structure 300 at two different locations, andbridges up and over islands 305 and 304 without making electricalcontact to islands 305 and 304. FIG. 15 is a diagram of the bottom DMBstructure 300. The bottom direct bonded metal layer of the DMB structure300 is patterned into two parallel-extending islands 316 and 317.Islands 316 and 317 are of the same width as islands 54 and 55 so thatwhen the DMB structure 300 is placed down onto the substrate DMBstructure 53, island 317 makes electrical contact with island 54 but notwith island 55, and island 316 makes electrical contact with island 55but not with island 54. Major and independent current flows cantherefore pass in the vertical dimension underneath the DMB structure300 through the two parallel-extending strip-shaped islands 54 and 55.The gate and auxiliary emitter electrical connection paths being madeacross the top of the DMB structure 300 are relatively low current pathsas compared to the relatively high current flows underneath the DMBstructure 300 through strip-shaped islands 54 and 55.

FIG. 16 is a diagram of another embodiment of a bridging DMB structure400. The bottom of the bridging DMB structure 400 of FIG. 16 is the sameas the bottom of bridging DMB structure 300 as illustrated in FIG. 15.Reference numeral 401 identifies the rectangular-shaped center ceramiclayer. The upper direct bonded metal layer of the DMB structure 400 ispatterned into four islands 402-405 having shapes as illustrated in FIG.16.

Although certain specific embodiments are described above forinstructional purposes, the teachings of this patent document havegeneral applicability and are not limited to the specific embodimentsdescribed above. Although bond wires are shown making connections to andthrough and over bridging DMB structures in the embodiments describedabove, bond wires need not be used. In some examples, clips are used orbonding ribbon. Although the example of the substrate DMB structure inthe novel module set forth above that has a direct bonded metal layerdisposed on the bottom side of its ceramic layer, the bottom directbonded metal layer is optional and in other examples the substrate DMBstructure has no such bottom direct bonded metal layer. Although thereis no semiconductor device mounted to the top of the two bridging DMBstructures described above, in another example an additional gateresistor chip is mounted to the top of a bridging DMB structure. Thisgate resistor chip is a small rectangular piece of silicon. The gateresistor chip is attached to straddle two lanes on the top of the DMB.One end of the gate resistor chip is coupled to the IGBT gate bondingwire that in turn extends to the gate of the IGBT. Accordingly, variousmodifications, adaptations, and combinations of various features of thedescribed embodiments can be practiced without departing from the scopeof the invention as set forth in the claims.

What is claimed is:
 1. A power semiconductor module comprising: a metalbaseplate; a first direct bonded metal (DMB) structure that is disposedon the metal baseplate, wherein the first DMB comprises a ceramic layer,a first direct bonded metal layer disposed on a bottom side of theceramic layer in thermal contact with the metal baseplate, a firstisland of a second direct bonded metal layer disposed on a top side ofthe ceramic layer, and a second island of the second direct bonded metallayer disposed on the top side of the ceramic layer; a semiconductordevice that is disposed on the first island of the second direct bondedmetal layer of the first DMB structure; a second DMB structure that isdisposed on the second island of the second direct bonded metal layer ofthe first DMB structure, wherein the second DMB structure comprises aceramic layer, a third direct bonded metal layer disposed on a bottomside of the ceramic layer of the second DMB structure, and a fourthdirect bonded metal layer disposed on a top side of the ceramic layer ofthe second DMB structure, wherein the third direct bonded metal layer ofthe second DMB structure is disposed on the second island of the seconddirect bonded metal layer of the first DMB structure, and wherein nosemiconductor device is disposed on the second DMB structure; a firstexternal connection terminal; a second external connection terminal; afirst bonding wire that connects the first external connection terminalto a first bonding location on the fourth direct bonded metal layer ofthe second DMB structure; a second bonding wire that connects a secondbonding location on the fourth direct bonded metal layer of the secondDMB structure to the semiconductor device; and a third bonding wire thatextends from the second external connection terminal over the fourthdirect bonded metal layer of the second DMB structure without contactingany portion of the fourth direct bonded metal layer of the second DMBstructure.
 2. The power semiconductor module of claim 1, furthercomprising: a second semiconductor device, wherein the third bondingwire electrically couples the second external connection terminal to thesecond semiconductor device.
 3. The power semiconductor module of claim1, wherein the third bonding wire couples the second external connectionterminal to the semiconductor device.
 4. The power semiconductor moduleof claim 1, wherein the fourth direct bonded metal layer of the secondDMB structure is an elongated strip of metal.
 5. The power semiconductormodule of claim 1, wherein the second island of the second direct bondedmetal layer of the first DMB structure conducts one of a main emittercurrent and a collector current, and wherein no part of the fourthdirect bonded metal layer of the second DMB structure carries a mainemitter current or a collector current.
 6. The power semiconductormodule of claim 1, wherein the second island of the second direct bondedmetal layer of the first DMB structure conducts one of a source currentand a drain current, and wherein no part of the fourth direct bondedmetal layer of the second DMB structure carries a source current or adrain current.
 7. The power semiconductor module of claim 1, wherein thethird bonding wire extends over a portion of the fourth direct bondedmetal layer that is disposed between the first bonding location and thesecond bonding location.
 8. The power semiconductor module of claim 1,wherein a bonding wire extends from a bonding location on the second DMBstructure to another bonding location on the second DMB structure. 9.The power semiconductor module of claim 8, wherein a bridging bondingwire extends from a bonding location on the second DMB structure, andthen bridges up and over but does not contact the fourth direct bondedmetal layer of the second DMB structure, and then bonds to anotherbonding location on the second DMB structure.
 10. The powersemiconductor module of claim 9, wherein the bridging bonding wirefurther extends from the second DMB structure to a second semiconductordevice of the power semiconductor module.
 11. The power semiconductormodule of claim 9, wherein the bridging bonding wire further extendsfrom the second DMB structure to a third external connection terminal ofthe power semiconductor module.
 12. The power semiconductor module ofclaim 11, wherein the second direct bonded metal layer of the first DMBstructure further comprises a third island, wherein the first and thirdislands of the second direct bonded metal layer of the first DMBstructure are electrically isolated from one other.
 13. A powersemiconductor module comprising: a metal baseplate; a first directbonded metal (DMB) structure that is disposed on the metal baseplate,wherein the first DMB comprises a ceramic layer, a first direct bondedmetal layer disposed on a bottom side of the ceramic layer in thermalcontact with the metal baseplate, and a second direct bonded metal layerdisposed on a top side of the ceramic layer; a semiconductor device thatis disposed on the first DMB structure; a second DMB structure that isdisposed on the first DMB structure, wherein there is no semiconductordevice disposed on the second DMB structure, wherein the second DMBstructure comprises a ceramic layer, a third direct bonded metal layerdisposed on a bottom side of the ceramic layer, and a fourth directbonded metal layer disposed on a top side of the ceramic layer; a firstbonding wire that is bonded to the second DMB structure at a firstlocation on the second DMB structure; and a second bonding wire that isbonded to the second DMB structure at a second location on the secondDMB structure.
 14. The power semiconductor module of claim 13, whereinthe fourth direct bonded metal layer of the second DMB structurecomprises a first elongated strip island portion and a second elongatedstrip island portion, and wherein the first and second elongated stripisland portions extend parallel to one another.
 15. The powersemiconductor module of claim 13, wherein the third direct bonded metallayer of the second DMB structure comprises a first island portion and asecond island portion.
 16. The power semiconductor module of claim 13,further comprising: a third bonding wire that extends over the secondDMB structure between the first and second locations on the second DMBstructure, and wherein the third bonding wire does not contact anyportion of the second DMB structure.
 17. The power semiconductor moduleof claim 13, further comprising: a third bonding wire that is bonded toa first island portion of the fourth direct metal bonded metal layer ofthe second DMB structure, that bridges over a second island portion ofthe fourth direct metal bonded metal layer of the second DMB structure,and that is bonded to a third island portion of the fourth direct metalbonded metal layer of the second DMB structure.
 18. The powersemiconductor module of claim 13, wherein the discrete semiconductordevice has a major top surface area, and wherein the second DMBstructure has a major top surface area, wherein the major top surfacearea of the discrete semiconductor device is larger than the major topsurface area of the second DMB structure.
 19. A power semiconductormodule comprising: a substrate Direct Metal Bonded (DMB) structure thatcomprises a ceramic layer and a direct bonded metal layer disposed on atop side of the ceramic layer; a power semiconductor device disposed onthe substrate DMB structure, wherein the power semiconductor device diehas a major top surface area; a bridging DMB structure that is disposedon the substrate DMB structure, wherein there is no semiconductor devicedisposed on the bridging DMB structure, wherein the bridging DMBstructure comprises a ceramic layer, a direct bonded metal layer that isbonded to a bottom side of the ceramic layer of the bridging DMBstructure, and a direct bonded metal layer that is bonded to a top sideof the ceramic layer of the bridging DMB structure, wherein the bridgingDMB structure has a major top surface area, and wherein the major topsurface area of the power semiconductor device die is larger than themajor top surface area of the bridging DMB structure; a first bond wireor ribbon that is bonded to the bridging DMB structure at a firstlocation on the second DMB structure, wherein the first bond wire orribbon is not directly bonded to the substrate DMB structure; and asecond bond wire or ribbon that is bonded to the bridging DMB structureat a second location on the bridging DMB structure, wherein the secondbond wire or ribbon is not directly bonded to the substrate DMBstructure.
 20. The power semiconductor module of claim 19, wherein thesecond bond wire or ribbon extends from the second location on thebridging DMB structure to the power semiconductor device.